RFA: configure.in patch to support building newlib natively on x86 Linux

[DJ Delorie]

> !    case "$host" in
> !    i[3456]86-pc-linux*)

Why are you checking host here, instead of target?  It shouldn't
matter, but it looks funny to be checking $host to set target flags.

Also, you can avoid replicating the default case if you do this
instead:

    case "${target}-${is_cross_compiler}" in
    i[3456]86-pc-linux*-no)

> !        FLAGS_FOR_TARGET=`echo $FLAGS_FOR_TARGET | sed -e 's/-nostdinc/ /'`

That won't work if $FLAGS_FOR_TARGET starts with '-', which is likely.
Echo will think it's an option for echo itself.  You also don't take
into account flags like -nostdinc++.  How about this?

      FLAGS_FOR_TARGET=`echo " $FLAGS_FOR_TARGET " | sed -e 's/ -nostdinc / /'`